class: SubprocessMeta

[354:14] static extends: object

Generated metadata helpers for Subprocess class surfaces.

Methods

• properties ()

  Returns property metadata for Subprocess.

  • @r A list.

class: Subprocess

[57:7] extends: object

GSubprocess allows the creation of and interaction with child processes. Processes can be communicated with using standard GIO-style APIs (ie: [class@Gio.InputStream], [class@Gio.OutputStream]). There are GIO-style APIs to wait for process termination (ie: cancellable and with an asynchronous variant). There is an API to force a process to terminate, as well as a race-free API for sending UNIX signals to a subprocess. One major advantage that GIO brings over the core GLib library is comprehensive API for asynchronous I/O, such [method@Gio.OutputStream.splice_async]. This makes GSubprocess significantly more powerful and flexible than equivalent APIs in some other languages such as the subprocess.py included with Python. For example, using GSubprocess one could create two child processes, reading standard output from the first, processing it, and writing to the input stream of the second, all without blocking the main loop. A powerful [method@Gio.Subprocess.communicate] API is provided similar to the communicate() method of subprocess.py. This enables very easy interaction with a subprocess that has been opened with pipes. GSubprocess defaults to tight control over the file descriptors open in the child process, avoiding dangling-FD issues that are caused by a simple fork()/exec(). The only open file descriptors in the spawned process are ones that were explicitly specified by the GSubprocess API (unless G_SUBPROCESS_FLAGS_INHERIT_FDS was specified). GSubprocess will quickly reap all child processes as they exit, avoiding ‘zombie processes’ remaining around for long periods of time. [method@Gio.Subprocess.wait] can be used to wait for this to happen, but it will happen even without the call being explicitly made. As a matter of principle, GSubprocess has no API that accepts shell-style space-separated strings. It will, however, match the typical shell behaviour of searching the PATH for executables that do not contain a directory separator in their name. By default, the PATH of the current process is used. You can specify G_SUBPROCESS_FLAGS_SEARCH_PATH_FROM_ENVP to use the PATH of the launcher environment instead. GSubprocess attempts to have a very simple API for most uses (ie: spawning a subprocess with arguments and support for most typical kinds of input and output redirection). See [ctor@Gio.Subprocess.new]. The [class@Gio.SubprocessLauncher] API is provided for more complicated cases (advanced types of redirection, environment variable manipulation, change of working directory, child setup functions, etc). A typical use of GSubprocess will involve calling [ctor@Gio.Subprocess.new], followed by [method@Gio.Subprocess.wait_async] or [method@Gio.Subprocess.wait]. After the process exits, the status can be checked using functions such as [method@Gio.Subprocess.get_if_exited] (which are similar to the familiar WIFEXITED-style POSIX macros). Note that as of GLib 2.82, creating a GSubprocess causes the signal SIGPIPE to be ignored for the remainder of the program. If you are writing a command-line utility that uses GSubprocess, you may need to take into account the fact that your program will not automatically be killed if it tries to write to stdout after it has been closed.

Members

• handleObj
• lib
• retainedCallbacks
• signalHandlerNames
• signalSetterHandlers

Methods

• Subprocess (argv = null, flags = null)

  Create a new process with the given flags and argument list. The argument list is expected to be %NULL-terminated.

  • @p argv is commandline arguments for the subprocess.
  • @p flags is flags that define the behaviour of the subprocess.

• toNativeHandle (Source)

  Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from fn.call(...), another generated wrapper exposing handle(), or null. Returns null when the argument carries no pointer.

  • @p Source is the raw handle, raw buffer, wrapper, or null.
  • @r A raw pointer carrier or null when no pointer is present.

• getLib ()

  Returns the opened native library for this generated wrapper.

  • @r The opened native library.

• handle ()

  Returns the wrapped NativeHandle.

  • @r The wrapped NativeHandle.

• isNull ()

  Returns true when the wrapped handle is null.

  • @r A bool.

• describe ()

  Returns a small string for debugging generated wrappers.

  • @r A string.

• asObject ()

  Wraps this handle as Object.

  • @r A Object object.

• asInitable ()

  Wraps this handle as Initable.

  • @r A Initable object.

• force_exit ()

  Use an operating-system specific method to attempt an immediate, forceful termination of the process. There is no mechanism to determine whether or not the request itself was successful; however, you can use g_subprocess_wait() to monitor the status of the process after calling this function. On Unix, this function sends %SIGKILL.

  • @r None.

• get_exit_status ()

  Check the exit status of the subprocess, given that it exited normally. This is the value passed to the exit() system call or the return value from main. This is equivalent to the system WEXITSTATUS macro. It is an error to call this function before g_subprocess_wait() and unless g_subprocess_get_if_exited() returned %TRUE.

• get_identifier ()

  On UNIX, returns the process ID as a decimal string. On Windows, returns the result of GetProcessId() also as a string. If the subprocess has terminated, this will return %NULL.

• get_if_exited ()

  Check if the given subprocess exited normally (ie: by way of exit() or return from main()). This is equivalent to the system WIFEXITED macro. It is an error to call this function before g_subprocess_wait() has returned.

• get_if_signaled ()

  Check if the given subprocess terminated in response to a signal. This is equivalent to the system WIFSIGNALED macro. It is an error to call this function before g_subprocess_wait() has returned.

• get_status ()

  Gets the raw status code of the process, as from waitpid(). This value has no particular meaning, but it can be used with the macros defined by the system headers such as WIFEXITED. It can also be used with g_spawn_check_wait_status(). It is more likely that you want to use g_subprocess_get_if_exited() followed by g_subprocess_get_exit_status(). It is an error to call this function before g_subprocess_wait() has returned.

• get_stderr_pipe ()

  Gets the #GInputStream from which to read the stderr output of

  • @subprocess. The process must have been created with %G_SUBPROCESS_FLAGS_STDERR_PIPE, otherwise %NULL will be returned.

• get_stdin_pipe ()

  Gets the #GOutputStream that you can write to in order to give data to the stdin of @subprocess. The process must have been created with %G_SUBPROCESS_FLAGS_STDIN_PIPE and not %G_SUBPROCESS_FLAGS_STDIN_INHERIT, otherwise %NULL will be returned.

• get_stdout_pipe ()

  Gets the #GInputStream from which to read the stdout output of

  • @subprocess. The process must have been created with %G_SUBPROCESS_FLAGS_STDOUT_PIPE, otherwise %NULL will be returned.

• get_successful ()

  Checks if the process was "successful". A process is considered successful if it exited cleanly with an exit status of 0, either by way of the exit() system call or return from main(). It is an error to call this function before g_subprocess_wait() has returned.

• get_term_sig ()

  Get the signal number that caused the subprocess to terminate, given that it terminated due to a signal. This is equivalent to the system WTERMSIG macro. It is an error to call this function before g_subprocess_wait() and unless g_subprocess_get_if_signaled() returned %TRUE.

• send_signal (int signal_num)

  Sends the UNIX signal @signal_num to the subprocess, if it is still running. This API is race-free. If the subprocess has terminated, it will not be signalled. This API is not available on Windows.

  • @p signal_num is the signal number to send.
  • @r None.

• wait (object cancellable)

  Synchronously wait for the subprocess to terminate. After the process terminates you can query its exit status with functions such as g_subprocess_get_if_exited() and g_subprocess_get_exit_status(). This function does not fail in the case of the subprocess having abnormal termination. See g_subprocess_wait_check() for that. Cancelling

  • @cancellable doesn't kill the subprocess. Call g_subprocess_force_exit() if it is desirable.
  • @p cancellable is a #GCancellable.

• wait_check (object cancellable)

  Combines g_subprocess_wait() with g_spawn_check_wait_status().

  • @p cancellable is a #GCancellable.

• wait_check_finish (object result)

  Collects the result of a previous call to g_subprocess_wait_check_async().

  • @p result is the #GAsyncResult passed to your #GAsyncReadyCallback.

• wait_finish (object result)

  Collects the result of a previous call to g_subprocess_wait_async().

  • @p result is the #GAsyncResult passed to your #GAsyncReadyCallback.